Display apparatus and light source device thereof

ABSTRACT

A light source device comprises a diffuser plate and a light source module disposed behind the diffuser plate. The light source module includes a substrate, a plurality of light emitting diodes mounted on the substrate, and a plurality of reflective layers each provided on a front surface of the plurality of light emitting diodes. When a distance between the centers of each of the plurality of light emitting diodes is referred to as a pitch, and a distance between the diffuser plate and the substrate is referred to as an optical distance, a ratio of the pitch to the optical distance satisfies the following expression: 
       2.5≤pitch/optical distance≤4.5.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a bypass continuation application of InternationalApplication No. PCT/KR2021/002227, filed on Feb. 23 2021, which claimspriority from Korean Patent Application No. 10-2021-0000570, filed onJan. 4, 2021 and Korean Patent Application No. 10-2021-0015150, filed onFeb. 3, 2021, in the Korean Intellectual Property Office, and thisapplication also claims priority to Korean Patent Application No.10-2021-0070750, filed on Jun. 1, 2021, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND 1. Field

The present disclosure relates to a display apparatus and a light sourcedevice thereof, and more particularly, to a display apparatus includingan improved optical structure and a light source device thereof.

2. Description of Related Art

Generally, a display apparatus converts obtained or stored electricalinformation into visual information and displays the visual informationto a user. The display apparatus is used in various fields, such as homeor workplace.

The display apparatus includes a monitor apparatus connected to apersonal computer or a server computer, a portable computer device, anavigation terminal device, a general television apparatus, an InternetProtocol television (IPTV), a portable terminal device, such as a smartphone, a tablet PC, a personal digital assistant (PDA) or a cellularphone, various display apparatuses used to reproduce images, such asadvertisements or movies in an industrial field, or various kinds ofaudio/video systems.

The display apparatus includes a light source module configured toconvert electrical information into visual information, and the lightsource module includes a plurality of light sources configured toindependently emit light.

Each of the plurality of light sources includes, for example, a lightemitting diode (LED) or an organic light emitting diode (OLED). Forexample, the LED or the OLED may be mounted on a circuit board or asubstrate.

SUMMARY

The present disclosure is directed to providing a display apparatus at areduced cost.

Further, the present disclosure is directed to providing a displayapparatus with a reduced thickness.

An aspect of the present disclosure provides a light source deviceincluding a diffuser plate and a light source module disposed behind thediffuser plate. The light source module includes a substrate, aplurality of light emitting diodes mounted on the substrate, and aplurality of reflective layers each provided on a front surface of theplurality of light emitting diodes. When a distance between centers ofeach of the plurality of light emitting diodes is referred to as a pitchand a distance between the diffuser plate and the substrate is referredto as an optical distance, the pitch and the optical distance satisfythe following expression:

2.5≤pitch/optical distance≤4.5.

The light source module may include a plurality of optical domes eachconfigured to cover the plurality of light emitting diodes.

The plurality of reflective layers may be provided to allow main light,which is emitted from the plurality of light emitting diodes, to have anangle that is greater than or equal to 50° but less than or equal to 65°with respect to a front and rear direction.

The reflective layer may be provided as a Distributed Bragg Reflector(DBR).

The pitch may be greater than or equal to 4 mm but less than or equal to14 mm.

The optical distance may be greater than or equal to 1.5 mm but lessthan or equal to 4.5 mm.

The plurality of light emitting diodes may be arranged along a firstdirection and a second direction perpendicular to the first direction,and the pitch may be set to a first distance in the first direction thatis greater than a second distance in the second direction.

A relationship between first distance in the first direction and thesecond distance in the second direction satisfies the followingexpression:

(first distance)≤1.1*(second distance).

If the pitch is a maximum value and the optical distance is greater thanor equal to 1.5 mm but less than or equal to 2.5 mm, a ratio of thepitch to the optical distance satisfies the following expression:

3.5≤pitch/optical distance≤4.5.

If the pitch is a maximum value and the optical distance is greater thanor equal to 2.5 mm but less than or equal to 3.5 mm, a ratio of thepitch to the optical distance satisfies the following expression:

3.2≤pitch/optical distance≤4.2.

If the pitch is a maximum value and the optical distance is greater thanor equal to 3.5 mm but less than or equal to 4.5 mm, a ratio of thepitch to the optical distance satisfies the following expression:

2.5≤pitch/optical distance≤3.5.

The plurality of optical domes may be formed of silicone or epoxy resin.

The light emitting diode may be configured to emit blue light.

Another aspect of the present disclosure provides a display apparatusincluding a light source device configured to output light, and a liquidcrystal panel configured to block or transmit the light. The lightsource device includes a diffuser plate and a light source moduledisposed behind the diffuser plate. The light source module includes asubstrate, a plurality of light emitting diodes mounted on the substrateand arranged along a first direction and a second direction differentfrom the first direction, and a plurality of optical domes eachconfigured to cover the plurality of light emitting diodes. When adistance between centers of each of the plurality of light emittingdiodes is referred to as a pitch and a distance between the diffuserplate and the substrate is referred to as an optical distance, a ratioof the pitch to the optical distance satisfies the following expression:

2.2≤pitch/optical distance≤4.5.

The light source module may include a plurality of reflective layerseach provided on a front surface of the plurality of light emittingdiodes.

The plurality of reflective layers may be provided to allow mainoptical, which is emitted from the plurality of light emitting diodes,to have an angle that is greater than or equal to 50° but less than orequal to 65° with respect to a front and rear direction.

The pitch may be set to a first distance in the first direction that isgreater than a second distance in the second direction and arelationship between the first distance in the first direction and thesecond distance in the second direction satisfies the followingexpression:

(first distance)≤1.1*(second distance).

When the pitch is a maximum value and the optical distance is greaterthan or equal to 1.5 mm but less than or equal to 2.5 mm, a ratio thepitch to the optical distance satisfies the following expression:

3.523 pitch/optical distance≤4.5.

When the pitch is a maximum value and the optical distance is greaterthan or equal to 2.5 mm but less than or equal to 3.5 mm, a ratio of thepitch to the optical distance may satisfies the following expression:

3.2≤pitch/optical distance≤4.2.

When the pitch is a maximum value and the optical distance is greaterthan or equal to 3.5 mm but less than or equal to 4.5 mm, a ratio of thepitch to the optical distance satisfies the following expression:

2.2≤pitch/optical distance≤3.5.

Another embodiment of the disclosure provides a light source deviceincluding: a diffuser plate; and a light source module disposed behindthe diffuser plate, wherein the light source module includes: asubstrate; a plurality of light emitting diodes mounted on thesubstrate; and a plurality of reflective layers provided on a frontsurface of the plurality of light emitting diodes, and wherein, when adistance between centers of the plurality of light emitting diodes is apitch, and a distance between the diffuser plate and the substrate is asan optical distance, a ratio of the pitch to the optical distancesatisfies the following expression:

2.5≤pitch/optical distance≤4.5.

According to yet another embodiment of the disclosure, a displayapparatus includes a light source device configured to output light; anda liquid crystal panel configured to block or transmit the light,wherein the light source device includes: a diffuser plate; and a lightsource module disposed behind the diffuser plate, wherein the lightsource module includes: a substrate; a plurality of light emittingdiodes mounted on the substrate and arranged along a first direction anda second direction different from the first direction; and a pluralityof optical domes configured to cover the plurality of light emittingdiodes, and wherein, when a distance between centers of the plurality oflight emitting diodes is a pitch, and a distance between the diffuserplate and the substrate is an optical distance, a ratio of the pitch tothe optical distance satisfies the following expression:

2.2≤pitch/optical distance≤4.5.

In yet another aspect of the disclosure a display apparatus includes alight source device configured to output light; a liquid crystal panelconfigured to block or transmit the light. The light source deviceincluding a diffuser plate and a light source module disposed behind thediffuser plate. The light source module including a substrate, aplurality of light emitting diodes mounted on the substrate and arrangedalong a first direction and a second direction different from the firstdirection, and a plurality of optical domes configured to cover theplurality of light emitting diodes. When pitch is defined as a distancebetween centers of adjacent light emitting diodes on the substrate andoptical distance is defined as a distance between the diffuser plate andthe substrate, a ratio of the pitch to the optical distance satisfiesthe following expression:

3.5≤pitch/optical distance≤4.5, and

wherein the plurality of reflective layers output light emitted from theplurality of light emitting diodes, with a full width half maximum thatis greater than or equal to 50° but less than or equal to 65°.

The display apparatus described herein may include a reduced number oflight sources, thereby reducing a cost of the display apparatus.

The display apparatus described herein has a reduced optical distance,thereby reducing a thickness of the display apparatus.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a view of an appearance of a display apparatus according to anembodiment of the present disclosure.

FIG. 2 is an exploded view of the display apparatus shown in FIG. 1according to an embodiment.

FIG. 3 is a side sectional view of a liquid crystal panel of the displayapparatus shown in FIG. 2 according to an embodiment.

FIG. 4 is an exploded view of a light source device shown in FIG. 2according to an embodiment.

FIG. 5 is a view illustrating coupling between a light source moduleincluded in the light source device, and a reflective sheet according toan embodiment.

FIG. 6 is a perspective view of a light source included in the lightsource device shown in FIG. 4 according to an embodiment.

FIG. 7 is an exploded view of the light source shown in FIG. 6 accordingto an embodiment.

FIG. 8 is a sectional view taken along line A-A′ shown in FIG. 6according to an embodiment.

FIG. 9 is a view illustrating a profile of light emitted from a lightemitting diode shown in FIG. 8 according to an embodiment.

FIG. 10 is a view illustrating a front surface of the light sourcemodule shown in FIG. 4 according to an embodiment.

FIG. 11 is a view illustrating a relationship between the light sourcemodule shown in FIG. 4 and a diffuser plate according to an embodiment.

FIG. 12 is a view illustrating an experimental result when a numericalrange of a pitch/an optical distance of a display apparatus is out of anumerical range according to an embodiment.

FIG. 13 is a view illustrating an experimental result when a numericalrange of a pitch/an optical distance of a display apparatus is within anumerical range according to an embodiment.

DETAILED DESCRIPTION

In the following description, like reference numerals refer to likeelements throughout the specification. Well-known functions orconstructions are not described in detail since they would obscure theone or more exemplary embodiments with unnecessary detail. Terms such as“unit”, “module”, “member”, and “block” may be embodied as hardware orsoftware. According to embodiments, a plurality of “units”, “modules”,“members”, and “blocks” may be implemented as a single component or asingle “unit”, “module”, “member”, and “block” and may also include aplurality of components.

When an element is referred to as being “connected” to another element,it is directly or indirectly connected to the other element, wherein theindirect connection includes “connection via a wireless communicationnetwork”.

Also, when a part “includes” or “comprises” an element, unless there isa particular description contrary thereto, the part may further includeadditional elements, not excluding the other elements.

When a first member is “on” a second member, the first member is incontact with the second member, but also includes when a third memberbetween the first and second members.

Although the terms first, second, third, etc., may be used herein todescribe various elements, the elements should not be limited by theseterms. These terms are only used to distinguish one element from anotherelement.

As used herein, the singular forms “a,” “an” and “the” include theplural forms of the words, unless the context clearly indicatesotherwise.

An identification code is used for the convenience of the descriptionbut is not intended to illustrate the order of each step. Each step maybe implemented in an order different from the illustrated order unlessthe context clearly indicates otherwise.

Hereinafter exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a view depicting a display apparatus according to oneembodiment of the disclosure.

A display apparatus 10 is a device that processes an image signalreceived from an outside source and visually displays the processedimage. Hereinafter an embodiment of a display apparatus 10 that is atelevision is described, but the disclosure is not limited thereto. Forexample, the display apparatus 10 may be implemented in various forms,such as a monitor, a portable multimedia device, and a portablecommunication device, and the display apparatus 10 is not limited in itsshape as long as the display apparatus 10 visually displays an image.

The display apparatus 10 may be a large format display (LFD) installedoutdoors, such as a roof of a building or a bus stop. The LFD displayapparatus 10 is not limited to the outside of a building, and thus thedisplay apparatus 10 may be installed in any place where the displayapparatus is viewable by a large number of people, including indoors, insubway stations, shopping malls, movie theaters, companies, and stores.

The display apparatus 10 may receive content data including video dataand audio data from various content sources and output video and audiocorresponding to the video data and the audio data. For example, thedisplay apparatus 10 may receive content data through a broadcastreception antenna or cable, receive content data from a content playbackdevice, or receive content data from a content provider's contentserver.

As illustrated in FIG. 1, the display apparatus 10 includes a body 11, ascreen 12 configured to display an image I, and a supporter 19 providedbelow the body 11 and configured to support the body 11.

The body 11 may form an appearance, e.g., a border, of the displayapparatus 10, and the body 11 may include a component configured toallow the display apparatus 10 to display the image I and to performvarious functions. Although the body 11 shown in FIG. 1 is in the formof a flat plate, the shape of the body 11 is not limited thereto. Forexample, the body 11 may have a curved plate shape.

The screen 12 may be formed on a front surface of the body 11, anddisplay the image I. For example, the screen 12 may display a stillimage or a moving image. Further, the screen 12 may display atwo-dimensional plane image or a three-dimensional image to the user byusing binocular parallax.

A plurality of pixels P may be formed on the screen 12 and the image Idisplayed on the screen 12 may be formed by the light emitted from theplurality of pixels P. For example, a single still image may be formedon the screen 12 by combining light emitted from the plurality of pixelsP as a mosaic.

Each of the plurality of pixels P may emit different brightness anddifferent color of light. In order to emit different brightness oflight, each of the plurality of pixels P may include a self-emissionpanel (for example, a light emitting diode panel) configured to directlyemit light or a non-self-emission panel (for example, a liquid crystalpanel) configured to transmit or block light emitted by a light sourcedevice.

To emit light in the various colors, the plurality of pixels P includesub-pixels P_(R), P_(G), and P_(B), respectively.

The sub-pixels may include a red sub pixel PR for emitting red light, agreen sub pixel PG for emitting green light, and a blue sub pixel P_(B)for emitting blue light. For example, the red light may represent alight beam having a wavelength of approximately 620 nm (nanometers, onebillionth of a meter) to 750 nm, the green light may represent a lightbeam having a wavelength of approximately 495 nm to 570 nm, and the bluelight may represent a light beam having a wavelength of approximately450 nm to 495 nm.

By combining the red light of the red sub pixel P_(R), the green lightof the green sub pixel P_(G), and the blue light of the blue sub pixelP_(B), each of the plurality of pixels P may emit different brightnessand different color of light.

FIG. 2 is an exploded view of the display apparatus shown in FIG. 1according to an exemplary embodiment.

As shown in FIG. 2, various components configured to generate the imageI on the screen S may be provided inside the body 11.

The body 11 includes a light source device 100 that is a surface lightsource, a liquid crystal panel 20 configured to block or transmit lightemitted from the light source device 100, a control assembly 50configured to control an operation of the light source device 100 andthe liquid crystal panel 20, and a power assembly 60 configured tosupply power to the light source device 100 and the liquid crystal panel20. Further, the body 11 includes a bezel 13, a frame middle mold 14, abottom chassis 15, and a rear cover 16 which are configured to supportand fix the liquid crystal panel 20, the light source device 100, thecontrol assembly 50, and the power assembly 60.

The light source device 100 may include a point light source configuredto emit monochromatic light or white light. The light source device 100may refract, reflect, and scatter light in order to convert light, whichis emitted from the point light source, into uniform surface light. Forexample, the light source device 100 may include a plurality of lightsources configured to emit monochromatic light or white light, adiffuser plate configured to diffuse light incident from the pluralityof light sources, a reflective sheet configured to reflect light emittedfrom the plurality of light sources and a rear surface of the diffuserplate, and an optical sheet configured to refract and scatter lightemitted from the front surface of the diffuser plate.

As mentioned above, the light source device 100 may refract, reflect,and scatter light emitted from the light source, thereby emittinguniform surface light toward the front.

A configuration of the light source device 100 will be described in moredetail below.

FIG. 3 is a side sectional view of a liquid crystal panel of the displayapparatus shown in FIG. 2 according to an exemplary embodiment.

The liquid crystal panel 20 is provided in front of the light sourcedevice 100 and blocks or transmits light emitted from the light sourcedevice 100 to form the image I.

A front surface of the liquid crystal panel 20 may form the screen 12 ofthe display apparatus 10 described above, and the liquid crystal panel20 may form the plurality of pixels P. In the liquid crystal panel 20,the plurality of pixels P may independently block or transmit light fromthe light source device 100, and the light transmitted through theplurality of pixels P may form the image I displayed on the screen 12.

For example, as shown in FIG. 3, the liquid crystal panel 20 may includea first polarizing film 21, a first transparent substrate 22, a pixelelectrode 23, a thin film transistor 24, a liquid crystal layer 25, acommon electrode 26, a color filter 27, a second transparent substrate28, and a second polarizing film 29.

The first transparent substrate 22 and the second transparent substrate28 may fixedly support the pixel electrode 23, the thin film transistor24, the liquid crystal layer 25, the common electrode 26, and the colorfilter 27. The first and second transparent substrates 22 and 28 may beformed of tempered glass or transparent resin.

The first polarizing film 21 and the second polarizing film 29 areprovided on the outside of the first and second transparent substrates22 and 28.

Each of the first polarizing film 21 and the second polarizing film 29may transmit a specific light beam and block other light beams. Forexample, the first polarizing film 21 transmits a light beam having amagnetic field vibrating in a first direction and blocks other lightbeams. In addition, the second polarizing film 29 transmits a light beamhaving a magnetic field vibrating in a second direction and blocks otherlight beams. In this case, the first direction and the second directionmay be perpendicular to each other. Accordingly, a polarizationdirection of the light transmitted through the first polarizing film 21and a vibration direction of the light transmitted through the secondpolarizing film 29 are perpendicular to each other. As a result, ingeneral, light may not pass through the first polarizing film 21 and thesecond polarizing film 29 at the same time.

The color filter 27 may be provided inside the second transparentsubstrate 28.

The color filter 27 may include a red filter 27R transmitting red light,a green filter 27G transmitting green light, and a blue filter 27Gtransmitting blue light. The red filter 27R, the green filter 27G, andthe blue filter 27B may be disposed parallel to each other. A region inwhich the color filter 27 is formed corresponds to the pixel P describedabove. A region in which the red filter 27R is formed corresponds to thered sub-pixel P_(R), a region in which the green filter 27G is formedcorresponds to the green sub-pixel P_(G), and a region in which the bluefilter 27B is formed corresponds to the blue sub-pixel P_(B).

The pixel electrode 23 may be provided inside the first transparentsubstrate 22, and the common electrode 26 may be provided inside thesecond transparent substrate 28.

The pixel electrode 23 and the common electrode 26 may be formed of ametal material through which electricity is conducted, and the pixelelectrode 23 and the common electrode 26 may generate an electric fieldto change the arrangement of liquid crystal molecules 25 a forming theliquid crystal layer 25 as described below.

The pixel electrode 23 and the common electrode 26 may be formed of atransparent material, and may transmit light incident from the outside.For example, the pixel electrode 23 and the common electrode 26 mayinclude indium tin oxide (ITO), indium zinc oxide (IZO), silver nanowire(Ag nano wire), carbon nanotube (CNT), graphene, or poly(3,4-ethylenedioxythiophene) (PEDOT).

The thin film transistor (TFT) 24 is provided inside the secondtransparent substrate 22.

The TFT 24 may transmit or block a current flowing through the pixelelectrode 23. For example, an electric field may be formed or removedbetween the pixel electrode 23 and the common electrode 26 in responseto turning on (closing) or turning off (opening) the TFT 24.

The TFT 24 may be formed of poly-silicon, and may be formed bysemiconductor processes, such as lithography, deposition, and ionimplantation.

The liquid crystal layer 25 is formed between the pixel electrode 23 andthe common electrode 26, and the liquid crystal layer 25 is filled withthe liquid crystal molecules 25 a.

Liquid crystals represent an intermediate state between a solid(crystal) and a liquid. Most of the liquid crystal materials are organiccompounds, and the molecular shape is in the shape of an elongated rod.The arrangement of molecules is in an irregular state in one direction,but may have a regular crystal shape in other directions. As a result,the liquid crystal has both the fluidity of the liquid and the opticalanisotropy of the crystal (solid).

In addition, liquid crystals also exhibit optical properties accordingto changes in an electric field. For example, in the liquid crystal, thedirection of the arrangement of molecules forming the liquid crystal maychange according to a change in an electric field.

In response to an electric field being generated in the liquid crystallayer 25, the liquid crystal molecules 25 a of the liquid crystal layer25 may be arranged according to the direction of the electric field. Ifthe electric field is not being generated in the liquid crystal layer25, the liquid crystal molecules 25 a may be arranged irregularly orarranged along an alignment layer (not shown). As a result, the opticalproperties of the liquid crystal layer 25 may vary depending on thepresence or absence of the electric field passing through the liquidcrystal layer 25.

A cable 20 a configured to transmit image data to the liquid crystalpanel 20, and a display driver integrated circuit (hereinafter referredto as ‘driver IC’) 30 configured to process digital image data andoutput an analog image signal are provided at one side of the liquidcrystal panel 20.

The cable 20 a may electrically connect the control assembly 50 and/orthe power assembly 60 to the driver IC 30, and may also electricallyconnect the driver IC 30 to the liquid crystal panel 20. The cable 20 amay include a flexible flat cable or a film cable that is bendable.

The driver IC 30 may receive image data and power from the controlassembly 50 and/or the power assembly 60 through the cable 20 a. Thedriver IC 30 may transmit the image data and driving current to theliquid crystal panel 20 through the cable 20 a.

In addition, the cable 20 a and the driver IC 30 may be integrallyimplemented as a film cable, a chip on film (COF), or a tape carrierpackage (TCP). In other words, the driver IC 30 may be disposed on thecable 20 b. However, the disclosure is not limited thereto, and thedriver IC 30 may be disposed on the liquid crystal panel 20.

The control assembly 50 may include a control circuit configured tocontrol an operation of the liquid crystal panel 20 and the light sourcedevice 100. The control circuit may process image data received from anexternal content source, transmit the image data to the liquid crystalpanel 20, and transmit dimming data to the light source device 100.

The power assembly 60 may supply power to the liquid crystal panel 20and the light source device 100 to allow the light source device 100 tooutput surface light and to allow the liquid crystal panel 20 to blockor transmit the light of the light source device 100.

The control assembly 50 and the power assembly 60 may be implemented asa printed circuit board and various circuits mounted on the printedcircuit board. For example, the power circuit may include a capacitor, acoil, a resistance element, a processor, and a power circuit board onwhich the capacitor, the coil, the resistance element, and the processorare mounted. Further, the control circuit may include a memory, aprocessor, and a control circuit board on which the memory and theprocessor are mounted.

Hereinafter the light source device 100 will be described.

FIG. 4 is an exploded view of a light source device shown in FIG. 2according to an exemplary embodiment. FIG. 5 is a view illustratingcoupling between a light source module included in the light sourcedevice, and a reflective sheet.

The light source device 100 includes a light source module 110configured to generate light, a reflective sheet 120 configured toreflect light, a diffuser plate 130 configured to uniformly diffuselight, and an optical sheet 140 configured to improve luminance of lightthat is emitted.

The light source module 110 may include a plurality of light sources 111configured to emit light, and a substrate 112 configured to support theplurality of light sources 111.

The plurality of light sources 111 may be arranged in a predeterminedpattern to allow light to be emitted with uniform luminance. Theplurality of light sources 111 may be arranged in such a way that adistance between one light source and light sources adjacent thereto isthe same.

For example, as shown in FIG. 4, the plurality of light sources 111 maybe arranged in rows and columns. Accordingly, the plurality of lightsources may be arranged such that an approximately square is formed byfour adjacent light sources. In addition, any one light source may bedisposed adjacent to four light sources, and a distance between onelight source and four adjacent light sources may be approximately thesame.

Alternatively, the plurality of light sources may be disposed in aplurality of rows, and a light source belonging to each row may bedisposed at the center of two light sources belonging to an adjacentrow. Accordingly, the plurality of light sources may be arranged suchthat an approximately equilateral triangle is formed by three adjacentlight sources. In this case, one light source may be disposed adjacentto six light sources, and a distance between one light source and sixadjacent light sources may be approximately the same.

However, the pattern in which the plurality of light sources 111 isdisposed is not limited to the pattern described above, and theplurality of light sources 111 may be disposed in various patterns toallow light to be emitted with uniform luminance.

The light source 111 may employ an element configured to emitmonochromatic light (light of a specific wavelength, for example, bluelight) or white light (for example, a light of a mixture of red light,green light, and blue light) in various directions by receiving power.For example, the light source 111 may include a light emitting diode(LED).

The substrate 112 may fix the plurality of light sources 111 to preventa change in the position of the light source 111. Further, the substrate112 may supply power, which is for the light source 111 to emit light,to the light source 111.

The substrate 112 may support the plurality of light sources 111 and maybe configured with synthetic resin, tempered glass, or a printed circuitboard (PCB) on which a conductive power supply line for supplying powerto the light source 111 is formed.

The reflective sheet 120 may reflect light emitted from the plurality oflight sources 111 forward or in a direction close to the forwarddirection.

In the reflective sheet 120, a plurality of through holes 120 a areformed at positions corresponding to each of the plurality of lightsources 111 of the light source module 110. In addition, the lightsource 111 of the light source module 110 may pass through the throughhole 120 a and protrude to the front of the reflective sheet 120.

For example, as shown in the upper portion of FIG. 5, in the process ofassembling the reflective sheet 120 and the light source module 110, theplurality of light sources 111 of the light source module 110 areinserted into the through holes 120 a formed on the reflective sheet120. Accordingly, as shown in the lower portion of FIG. 5, the substrate112 of the light source module 110 may be located behind the reflectivesheet 120, but the plurality of light sources 111 of the light sourcemodule 110 may be located in front of the reflective sheet 120.

Accordingly, the plurality of light sources 111 may emit light in frontof the reflective sheet 120.

The plurality of light sources 111 may emit light in various directionsfrom the front of the reflective sheet 120. The light may not only beemitted toward the diffuser plate 130 from the light source 111, butalso may be emitted toward the reflective sheet 120 from the lightsource 111. The reflective sheet 120 may reflect light, which is emittedtoward the reflective sheet 120, toward the diffuser plate 130.

Light emitted from the light source 111 passes through various objects,such as the diffuser plate 130 and the optical sheet 140. Among incidentlight beams passing through the diffuser plate 130 and the optical sheet140, some of the incident light beams are reflected from the surfaces ofthe diffuser plate 130 and the optical sheet 140. The reflective sheet120 may reflect light reflected by the diffuser plate 130 and theoptical sheet 140.

The diffuser plate 130 may be provided in front of the light sourcemodule 110 and the reflective sheet 120, and may evenly distribute thelight emitted from the light source 111 of the light source module 110.

As described above, the plurality of light sources 111 are located invarious places on the rear surface of the light source device 100.Although the plurality of light sources 111 are disposed at equalintervals on the rear surface of the light source device 100, unevennessin luminance may occur depending on the positions of the plurality oflight sources 111.

The diffuser plate 130 may diffuse light emitted from the plurality oflight sources 111 within the diffuser plate 130 in order to removeunevenness in luminance caused by the plurality of light sources 111. Inother words, the diffuser plate 130 may uniformly emit uneven light ofthe plurality of light sources 111 to the front surface.

The optical sheet 140 may include various sheets for improving luminanceand uniformity of luminance. For example, the optical sheet 140 mayinclude a diffusion sheet 141, a first prism sheet 142, a second prismsheet 143, and a reflective polarizing sheet 144.

The diffusion sheet 141 diffuses light for uniformity of luminance. Thelight emitted from the light source 111 may be diffused by the diffuserplate 130 and may be diffused again by the diffusion sheet 141 includedin the optical sheet 140.

The first and second prism sheets 142 and 143 may increase luminance bycondensing light diffused by the diffusion sheet 141. The first andsecond prism sheets 142 and 143 include a prism pattern in the shape ofa triangular prism, and a plurality of prism patterns are arrangedadjacent to each other to form a plurality of strips.

The reflective polarizing sheet 144 is a type of polarizing film and maytransmit some of the incident light beams and reflect others forimproving the luminance. For example, the reflective polarizing sheet144 may transmit polarized light in the same direction as apredetermined polarization direction of the reflective polarizing sheet144, and may reflect polarized light in a direction different from thepolarization direction of the reflective polarizing sheet 144. Inaddition, the light reflected by the reflective polarizing sheet 144 isrecycled inside the light source device 100, and thus the luminance ofthe display apparatus 10 may be improved by the light recycling.

The optical sheet 140 is not limited to the sheet or film shown in FIG.4, and may include more various sheets or films, such as a protectivesheet.

FIG. 6 is a perspective view of a light source included in the lightsource device shown in FIG. 4 according to an exemplary embodiment. FIG.7 is an exploded view of the light source shown in FIG. 6 according toan exemplary embodiment. FIG. 8 is a sectional view taken along lineA-A′ shown in FIG. 6 according to an exemplary embodiment.

The light source 111 of the light source device 100 will be describedwith reference to FIGS. 6 to 8.

As described above, the light source module 110 includes the pluralityof light sources 111. The plurality of light sources 111 may protrudeforward of the reflective sheet 120 from the rear of the reflectivesheet 120 by passing through the through hole 120 a. Accordingly, asshown in FIGS. 6 and 7, the light source 111 and a part of the substrate112 may be exposed toward the front of the reflective sheet 120 throughthe through hole 120 a.

The light source 111 may include an electrical/mechanical structurepositioned in a region defined by the through hole 120 a of thereflective sheet 120.

Each of the plurality of light sources 111 may include a light emittingdiode 210, an optical dome 220, and a reflective layer 260.

The light emitting diode 210 may include a P-type semiconductor and anN-type semiconductor for emitting light by recombination of holes andelectrons. In addition, the light emitting diode 210 is provided with apair of electrodes 210 a for supplying hole and electrons to the P-typesemiconductor and the N-type semiconductor, respectively.

The light emitting diode 210 may convert electrical energy into opticalenergy. In other words, the light emitting diode 210 may emit lighthaving a maximum intensity at a predetermined wavelength to which poweris supplied. For example, the light emitting diode 210 may emit bluelight having a peak value at a wavelength indicating blue (for example,a wavelength between 430 nm and 495 nm).

The light emitting diode 210 may be directly attached to the substrate112 in a Chip On Board (COB) method. In other words, the light source111 may include the light emitting diode 210 to which a light emittingdiode chip or a light emitting diode die is directly attached to thesubstrate 112 without an additional packaging.

To reduce the size of the light source 111, the light source module 110may be manufactured such that a flip-chip type light emitting diode 210is attached to the substrate 112 in a chip-on-board method.

On the substrate 112, a power supply line 230 and a power supply pad 240for supplying power to the flip-chip type light emitting diode 210 isprovided.

On the substrate 112, the power supply line 230 for supplying electricalsignals and/or power to the light emitting diode 210 from the controlassembly 50 and/or the power assembly 60 is provided.

As shown in FIG. 8, the substrate 112 may be formed by alternatelystacking an insulation layer 251 that is non-conductive and a conductionlayer 252 that is conductive.

A line or pattern, through which power and/or electrical signals pass,is formed on the conduction layer 252. The conduction layer 252 may beformed of various materials having electrical conductivity. For example,the conduction layer 252 may be formed of various metal materials, suchas copper (Cu), tin (Sn), aluminum (Al), or an alloy thereof.

A dielectric of the insulation layer 251 may insulate between lines orpatterns of the conduction layer 252. The insulation layer 251 may beformed of a dielectric for electrical insulation, for example, FR-4.

The power supply line 230 may be implemented by a line or pattern formedon the conduction layer 252.

The power supply line 230 may be electrically connected to the lightemitting diode 210 through the power supply pad 240.

The power supply pad 240 may be formed in such a way that the powersupply line 230 is exposed to the outside.

A protection layer 253 may be formed in the outermost part of thesubstrate 112 to prevent or suppress damages caused by an externalimpact, chemical action (for example, corrosion, etc.), and/or anoptical action. The protection layer 253 may include a photo solderresist (PSR).

As shown in FIG. 8, the protection layer 253 may cover the power supplyline 230 to prevent the power supply line 230 from being exposed to theoutside.

A window may be formed in the protection layer 253 to expose a part ofthe power supply line 230 to the outside to facilitate electricalcontact between the power supply line 230 and the light emitting diode210. A part of the power supply line 230 exposed to the outside throughthe window of the protection layer 253 may form the power supply pad240.

A conductive adhesive material 240 a for the electrical contact betweenthe power supply line 230 exposed to the outside and the electrode 210 aof the light emitting diode 210 is applied to the power supply pad 240.The conductive adhesive material 240 a may be applied within the windowof the protection layer 253.

The electrode 210 a of the light emitting diode 210 is in contact withthe conductive adhesive material 240 a, and the light emitting diode 210may be electrically connected to the power supply line 230 through theconductive adhesive material 240 a.

The conductive adhesive material 240 a may include a solder havingelectrical conductivity. However, the disclosure is not limited thereto,and the conductive adhesive material 240 a may include electricallyconductive epoxy adhesives.

Power may be supplied to the light emitting diode 210 to cause the lightemitting diode 210 to emit light through the power supply line 230 andthe power supply pad 240, and in response to the supply of the power. Apair of power supply pads 240 corresponding to each of the pair ofelectrodes 210 a provided in the flip chip type light emitting diode 210may be provided.

The optical dome 220 may cover the light emitting diode 210. The opticaldome 220 may prevent or suppress damages to the light emitting diode 210caused by an external mechanical action and/or damage to the lightemitting diode 210 caused by chemical action.

The optical dome 220 may have a dome shape formed in such a way that asphere is cut into a surface not including the center thereof, or mayhave a hemispherical shape in such a way that a sphere is cut into asurface including the center thereof. A vertical cross section of theoptical dome 220 may be a bow shape or a semicircle shape.

The optical dome 220 may be formed of silicone or epoxy resin. Forexample, the molten silicon or epoxy resin may be discharged onto thelight emitting diode 210 through a nozzle, and the discharged silicon orepoxy resin may be cured, thereby forming the optical dome 220.

Accordingly, the shape of the optical dome 220 may vary depending on theviscosity of the liquid silicone or epoxy resin. For example, when theoptical dome 220 is manufactured using silicon having a thixotropicindex of about 2.7 to 3.3 (appropriately, 3.0), the optical dome 220 isformed with a dome ratio (a height of the dome/a diameter of a base),which indicates a ratio of a height of a dome with respect to a diameterof a base of the dome, of approximately 0.25 to 0.31 (appropriately0.28). For example, the optical dome 220 formed of silicon having athixotropic index of approximately 2.7 to 3.3 (appropriately, 3.0) mayhave a diameter of approximately 2.5 mm and a height of approximately0.7 mm.

The optical dome 220 may be optically transparent or translucent. Lightemitted from the light emitting diode 210 may be emitted to the outsideby passing through the optical dome 220.

In this case, the dome-shaped optical dome 220 may refract light like alens. For example, light emitted from the light emitting diode 210 maybe refracted by the optical dome 220 and thus may be dispersed.

As mentioned above, the optical dome 220 may disperse light emitted fromthe light emitting diode 210 as well as protecting the light emittingdiode 210 from external mechanical and/or chemical or electricalactions.

The reflective layer 260 may be positioned in front of the lightemitting diode 210. The reflective layer 260 may be disposed on thefront surface of the light emitting diode 210. The reflective layer 260may be a multilayer reflective structure in which a plurality ofinsulation layers having different refractive indices is alternatelystacked. For example, the multilayer reflective structure may be aDistributed Bragg Reflector (DBR) in which a first insulation layerhaving a first refractive index and a second insulation layer having asecond refractive index are alternately stacked.

FIG. 9 is a view illustrating a profile of light emitted from a lightemitting diode shown in FIG. 8 according to an exemplary embodiment.

Specifically, a profile of light, which is light output information oflight emitted from the center of the light emitting diode 210 shown inFIG. 8, is illustrated in FIG. 9. Referring to FIG. 9, light emittedfrom the light emitting diode 210 may be diffused and emitted by thereflective layer 260 having reflective properties. In FIG. 9, the arrowsindicate the brightness of light where a longer arrow represents agreater brightness of light. In the profile of light shown in FIG. 9, alonger arrow represents a larger amount of light emission, and adirection in which a larger amount of light is emitted represents agreater brightness. In FIG. 9, a direction of a longest arrow, adirection in which a largest amount of light is emitted, i.e., adirection in which a greatest brightness is represented may be definedas a main optical path (M).

Particularly, the main optical path M of the light emitting diode 210may have an angle (a) that is greater than or equal to 50° but less thanor equal to 65° with respect to a front and rear direction. In anexemplary embodiment, the front and rear direction is an optical axis.That is, the angle between the main optical paths M may be greater thanor equal to 100° but less than or equal to 130°. Preferably, but notnecessarily, the main optical path M of the light emitting diode 210 mayhave an angle of 54° with respect to the front-rear direction. That is,the angle between the main optical paths M of the light emitting diode210 may be 108°.

FIG. 10 is a view illustrating a front surface of the light sourcemodule shown in FIG. 4 according to an exemplary embodiment. FIG. 11 isa view illustrating a relationship between the light source module shownin FIG. 4 and a diffuser plate according to an exemplary embodiment.

Hereinafter a distance between the approximately centers of each of theplurality of light emitting diodes 210 may be referred to as pitches xand y, and a distance between the diffuser plate 130 and the substrate112 may be referred to as an optical distance (OD) h.

A pitch x of the plurality of light sources 111 in the left and rightdirection may be greater than or equal to 4 mm but less than or equal to14 mm. Particularly, the pitch x of the centers of each of the pluralityof light sources 111 in the left and right direction may be greater thanor equal to 4 mm but less than or equal to 14 mm.

In addition, a pitch y of the plurality of light sources 111 in the upand down direction may be greater than or equal to 4 mm but less than orequal to 14 mm. Particularly, the pitch y of the centers of each of theplurality of light sources 111 in the up and down direction may begreater than or equal to 4 mm but less than or equal to 14 mm.

The pitch x of the centers of each of the plurality of light sources 111in the left and right direction may be different from the pitch y of thecenters of each of the plurality of light sources 111 in the up and downdirection. The pitch x of the centers of each of the plurality of lightsources 111 in the left and right direction may be greater than thepitch y of the centers of each of the plurality of light sources 111 inthe up and down direction, but may be less than or equal to 1.1 times ofthe pitch y of the centers of each of the plurality of light sources 111in the up and down direction. Alternatively, the pitch x of the centersof each of the plurality of light sources 111 in the left and rightdirection may be substantially the same as the pitch y of the centers ofeach of the plurality of light sources 111 in the up and down direction.The pitch x in the left and right direction and the pitch y in the upand down direction may satisfy the following expression:

(second distance)≤(first distance)≤1.1*(second distance).

Referring to FIG. 11, the optical distance h between the substrate 112and the diffuser plate 130 may be greater than or equal to 1.5 mm butless than or equal to 4.5 mm. Particularly, a distance from the frontsurface of the substrate 112 to the rear surface of the diffuser plate130 through the air layer may be greater than or equal to 1.5 mm butless than or equal to 4.5 mm.

The light source device 100 according to an embodiment of the presentdisclosure may be provided to allow the pitch x of the centers of eachof the plurality of light sources 111 in the left and right directionand the optical distance h between the substrate 112 and the diffuserplate 130 to satisfy the following expression. That is, in the lightsource device 100 according to an embodiment of the present disclosure,the pitch of the centers of each of the plurality of light sources 111in the left and right direction may be greater than or equal to 4 mm butless than or equal to 14 mm, and the optical distance h between thesubstrate 112 and the diffuser plate 130 may be greater than or equal to1.5 mm but less than or equal to 4.5 mm as shown by the followingexpression:

2.2≤(x)/h≤4.5.

Particularly, when the pitch x of the centers of each of the pluralityof light sources 111 in the left and right direction is 1.1 times thepitch y in the up and down direction, and when the optical distance hbetween the substrate 112 and the diffuser plate 130 is greater than orequal to 1.5 mm but less than or equal to 2.5 mm, the pitch x and theoptical distance h may satisfy the following expression:

3.5≤(x)_(max)/h≤4.5.

In addition, when the pitch x of the centers of each of the plurality oflight sources 111 in the left and right direction is 1.1 times the pitchy in the up and down direction, and when the optical distance h betweenthe substrate 112 and the diffuser plate 130 is greater than or equal to2.5 mm but less than or equal to 3.5 mm, the pitch x and the opticaldistance h may satisfy the following expression:

3.2≤(x)_(max)/h≤4.2.

In addition, when the pitch x in of the centers of each of the pluralityof light sources 111 the left and right direction is 1.1 times the pitchy in the up and down direction, and when the optical distance h betweenthe substrate 112 and the diffuser plate 130 is greater than or equal to3.5 mm but less than or equal to 4.5 mm, the pitch x and the opticaldistance h may satisfy the following expression:

2.2≤(x)_(max)/h≤3.5.

Preferably, but not necessarily, when the pitch x of the centers of eachof the plurality of light sources 111 in the left and right direction is1.1 times the pitch y of the centers of each of the plurality of lightsources 111 in the up and down direction, and the optical distance hbetween the substrate 112 and the diffuser plate 130 is greater than orequal to 3.5 mm but less than or equal to 4.5 mm, the pitch x and theoptical distance h may satisfy the following expression:

2.5≤(x)_(max)/h≤3.5.

Additionally, the display apparatus 10 according to an embodiment of thepresent disclosure may be provided such that the optical distance h maybe set to 3 mm, and the pitch x may be set to 9.8 mm. Accordingly, theratio of the pitch x to the optical distance h may be approximately3.27.

As for the display apparatus 10 according to an embodiment of thepresent disclosure, the optical distance h may be set to 3.1 mm, and thepitch x may be set to 11 mm. Accordingly, the ratio of the pitch x tothe optical distance h may be approximately 3.55.

Due to this configuration, the light source device 100 according to anembodiment of the present disclosure and the display apparatus 10, it ispossible to reduce the number of light sources in the display apparatus10, thereby securing cost competitiveness by minimizing the cost of thedisplay apparatus 10. In addition, the light source device 100 accordingto an embodiment of the present disclosure and the display apparatus 10,it is possible to reduce the optical distance h, thereby reducing thethickness of the display device 10.

FIG. 12 is a view illustrating an experimental result when a numericalrange of a pitch/an optical distance of a display apparatus is out of anumerical range according to an embodiment of the present disclosure.FIG. 13 is a view illustrating an experimental result when a numericalrange of a pitch/an optical distance of a display apparatus is within anumerical range according to an embodiment of the present disclosure.

Referring to FIG. 12, a moire phenomenon noticeably occurs when theratio of the pitch x to the optical distance h of the light sourcedevices of the display apparatus 100 is out of the numerical rangebelow:

2.5≤(x)/h≤4.5.

In contrast, as shown in FIG. 13, a moire phenomenon is remarkablyeliminated when the ratio of the pitch x to the optical distance h ofthe light source devices of the display apparatus 100 preferably, butnot necessarily, satisfies the numerical range below:

2.5≤(x)/h≤4.5.

While the present disclosure has been particularly described withreference to exemplary embodiments, it should be understood by those ofskilled in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present disclosure.

1. A light source device comprising: a diffuser plate; and a lightsource module disposed behind the diffuser plate, wherein the lightsource module comprises: a substrate; a plurality of light emittingdiodes mounted on the substrate; and a plurality of reflective layersprovided on a front surface of the plurality of light emitting diodes,and wherein, when a distance between centers of the plurality of lightemitting diodes is a pitch, and a distance between the diffuser plateand the substrate is an optical distance, a ratio of the pitch to theoptical distance satisfies the following expression:2.5≤pitch/optical distance≤4.5, wherein the plurality of light emittingdiodes is arranged along a first direction and a second directionperpendicular to the first direction, and wherein the first distance inthe first direction and the second distance in the second directionsatisfy the following expression:(first distance)≤1.1*(second distance).
 2. The light source device ofclaim 1, wherein the light source module comprises a plurality ofoptical domes configured to cover the plurality of light emittingdiodes.
 3. The light source device of claim 1, wherein the plurality ofreflective layers outputs main light, which is emitted from theplurality of light emitting diodes, to have an angle that is greaterthan or equal to 50° but less than or equal to 65° with respect to afront and rear direction.
 4. The light source device of claim 1, whereinthe plurality of reflective layers comprises a Distributed BraggReflector (DBR).
 5. The light source device of claim 1, wherein thepitch is greater than or equal to 4 mm but less than or equal to 14 mm.6. The light source device of claim 1, wherein the optical distance isgreater than or equal to 1.5 mm but less than or equal to 4.5 mm. 7-8.(canceled)
 9. The light source device of claim 1, wherein when the pitchis a maximum value and the optical distance is greater than or equal to1.5 mm but less than or equal to 2.5 mm, the ratio of the pitch to theoptical distance satisfies the following expression:3.5≤pitch/optical distance≤4.5.
 10. The light source device of claim 1,wherein when the pitch is a maximum value and the optical distance isgreater than or equal to 2.5 mm but less than or equal to 3.5 mm, theratio of the pitch to the optical distance satisfies the followingexpression:3.2≤pitch/optical distance≤4.2.
 11. The light source device of claim 1,wherein when the pitch is a maximum value and the optical distance isgreater than or equal to 3.5 mm but less than or equal to 4.5 mm, theratio of the pitch to the optical distance satisfies the followingexpression:2.5≤pitch/optical distance≤3.5.
 12. The light source device of claim 2,wherein the plurality of optical domes is formed of silicone or epoxyresin.
 13. The light source device of claim 1, wherein the plurality oflight emitting diodes is configured to emit blue light.
 14. A displayapparatus comprising: a light source device configured to output light;and a liquid crystal panel configured to block or transmit the light,wherein the light source device comprises: a diffuser plate; and a lightsource module disposed behind the diffuser plate, wherein the lightsource module comprises: a substrate; a plurality of light emittingdiodes mounted on the substrate and arranged along a first direction anda second direction different from the first direction; and a pluralityof optical domes configured to cover the plurality of light emittingdiodes, and wherein, when a distance between centers of the plurality oflight emitting diodes is a pitch, and a distance between the diffuserplate and the substrate is an optical distance, a ratio of the pitch tothe optical distance satisfies the following expression:2.2≤pitch/optical distance≤4.5, wherein the plurality of light emittingdiodes is arranged along a first direction and a second directionperpendicular to the first direction, and wherein the first distance inthe first direction and the second distance in the second directionsatisfy the following expression:(first distance)≤1.1*(second distance).
 15. The display apparatus ofclaim 14, wherein the light source module comprises a plurality ofreflective layers each provided on a front surface of the plurality oflight emitting diodes.
 16. A display apparatus comprising: a lightsource device configured to output light; a liquid crystal panelconfigured to block or transmit the light; and wherein the light sourcedevice comprises: a diffuser plate; and a light source module disposedbehind the diffuser plate, wherein the light source module comprises: asubstrate; a plurality of light emitting diodes mounted on the substrateand arranged along a first direction and a second direction differentfrom the first direction; and a plurality of optical domes configured tocover the plurality of light emitting diodes, and wherein, when pitch isdefined as a distance between centers of adjacent light emitting diodeson the substrate and optical distance is defined as a distance betweenthe diffuser plate and the substrate, a ratio of the pitch to theoptical distance satisfies the following expression:2.2≤pitch/optical distance≤4.5, and wherein the plurality of reflectivelayers output light emitted from the plurality of light emitting diodes,with a full width half maximum that is greater than or equal to 50° butless than or equal to 65°.
 17. The display apparatus of claim 16,wherein the light source module further comprises a plurality ofreflective layers provided on a front surface of the plurality of lightemitting diodes.
 18. The light source device of claim 16, whereinwherein the pitch is set to a first distance in the first direction thatis greater than a second distance in the second direction.
 19. Thedisplay apparatus of claim 18, wherein a relationship between the firstdistance and the second distance satisfies the following expression:(first distance)≤1.1*(second distance).